It’s also not nice to write longer text in monospace. Or to have long URLs interrupt the text just because you want a hyperlink on some word. Or having to lay out tables by hand like ASCII art. Seeing *this* isn’t the same as seeing this. And you need custom editor software anyway to have affordances like TOC navigation.
Tables by hand, I hate. But I don't quite agree with the first sentiment. For longform prose, it isn't that unusual for people to work with all editing marks visible. Writing novels, I absolutely write using monospace, because it allows you to more concisely control large amounts of formatting easily.
> long URLs interrupt the text just because you want a hyperlink
This annoyed me until I realized pandoc supports separating [the link text] from the link location.
Yep, but (a) that isn’t portable Markdown, (b) your editor probably doesn’t support opening the link from the link text in that case, and (c) whenever you want to modify the link text you have to modify all occurrences. A word processor can handle that automatically for you. It can also offer completion (like tab completion) for references that you use repeatedly. It can show as a tooltip what a given link text links to. Conveniences like that is what computers are for, let’s not relapse to the stone age here.